I updated a 5 to iOS 10 Using iTunes. Then I was asked to update carrier. Unsure of this update, I canceled. Now I can not access the carrier update. Without the carrier update, the phone does not access wi-fI for phone calls. How do I access the carrier update. It is not available in settings ... general ... about or in settings ... cellular. When I click software update I t just says phone is up to date With iOS 10.